It would be very useful have ability to merge activities from two or more sources. My primary use case: I use Rouvy virtual training and my Fenix 6X with my Taco Neo 2T for indoor training virtual rides. Rouvy has used the Connect API to automatically export its FIT file to Garmin Connect. Both provide power, speed, cadence, and distance. The Fenix captures info like performance Condition, L/R balance, Temperature, etc. and the Rouvy app provides virtual ride info (location tracks, altitude, etc.)
Is there any way to merge the two FIT files to provide one complete picture of the activity? There are a few websites (GOTOES, Fitfiletools) that attempt but are incomplete, and also require manual upload/download of FIT files.